A livid BJP came out strongly against Tharoor, saying it was an "attack on the Indian democracy and Hindus".

Congress leader Shashi Tharoor triggered a huge controversy with his remarks that if voted to power again, the Bharatiya Janata Party will rewrite the Constitution and pave the way for creation of a "Hindu Pakistan".

The comments by Tharoor sparked demands from the BJP for an apology from Congress president Rahul Gandhi for the "attack on Indian democracy and Hindus" while his party voiced its disapproval and cautioned its leaders to exercise restraint in their response to what it called the saffron party's "hatred".

"If they have been able to win a repeat of their current strength in the Lok Sabha, then frankly, our own democratic Constitution, as we understand, will not survive... because then they will have all the three elements they need to tear up the Constitution of India and write a new one.

"And that will enshrine the principle of Hindu Rashtra, that will remove equality for the minorities, and that will create a Hindu Pakistan...and that is not what Mahatma Gandhi, Nehru, Sardar Patel, Maulana Azad and great heroes of freedom struggle fought for," the Lok Sabha MP from Thiruvananthapuram told an event in the Kerala state capital on Wednesday.

Lok Sabha polls are due next year.

WATCH: What Shashi Tharoor had to say:

Unfazed by the controversy, a combative Tharoor took to Facebook on Thursday to defend his remarks, insisting that the BJP and RSS' idea of a Hindu Rashtra was the "mirror image" of Pakistan.

Defending himself, he told TV channels that he was “repeating what is on record” from the ruling party and its ideological mentor, the Rashtriya Swayamsewak Sangh.

“I don't see what exactly I need to apologise for the BJP's point of view ... If they are no longer interested in the idea of Hindu Rashtra they must admit. Until they do so, how can one apologise for reflecting their point accurately?" he said.

A livid BJP came out strongly against Tharoor with party spokesman Sambit Patra calling it "extraordinary" as it was an "attack on the Indian democracy and Hindus".

"Yet again Tharoor has cattle-classed Indian democracy. The Congress' character is that it crosses the 'Lakshman Rekha' (limit) in its hatred for Narendra Modi and the BJP, and in doing so, it assaults Indian democracy," he told reporters in Delhi.

"It is shameful to denigrate one's own country, one's own country's democracy, to denigrate the Hindu religion time and again.

"This is a shameful act for which Rahul Gandhi should come out and not only apologise but explain to us why any leader of that party, whenever they open their mouth, they speak this way," he said.

Tharoor had courted a controversy a few years ago when he was a minister at the Centre with his comment on Twitter that he would travel "cattle class out of solidarity with all our holy cows."

The comment had followed the then finance minister Pranab Mukherjee's advice to Congress leaders to observe austerity in order to cut down expenditure in the wake of drought in several parts of the country.

Patra said it was an insult to compare India's democracy to that of Pakistan, which he called "terroristan", and demanded that the Congress stop "fear-mongering".

In his post, Tharoor said many proud Hindus like him cherished the inclusive nature of the faith and had no desire to live, as their Pakistani neighbours were forced to, in an intolerant theocratic state. "We want to preserve India and not turn our beloved country into a Hindu version of Pakistan".

"I have said this before and I will say it again. Pakistan was created as a state with a dominant religion, that discriminates against its minorities and denies them equal rights. India never accepted the logic that had partitioned the country.

"But the BJP/RSS idea of a Hindu Rashtra is the mirror image of Pakistan a state with a dominant majority religion that seeks to put its minorities in a subordinate place. That would be a Hindu Pakistan, and it is not what our freedom movement fought for, nor the idea of India enshrined in our Constitution."

Congress's communication in-charge Randeep Surjewala, in a series of tweets, said, "India's values and fundamentals are an unequivocal guarantee of our civilisational role & set us apart from the divisive idea of Pakistan."

"All Congress leaders must realise this historic responsibility bestowed upon us while choosing words and phraseology to reject BJP's hatred," he said.

Responding to a question at the AICC briefing in Delhi, Congress spokesperson Jaiveer Shergill said that irrespective of the government that comes to power, Indian democracy will never allow the country to become Pakistan.

"Congress advises each of its leaders and workers to exercise restraint, caution, and choose their words and statements wisely. And remember that the Indian National Congress stands for a pluralistic multi-cultural, multi-faith society," Shergill said.

Tharoor, however, got some support from former vice president Hamid Ansari.

"I have not read what he (Tharoor) has said. But he is an educated man, a writer, an MP...and heads Parliament's committee on external affairs. Whatever he says, he will say after thorough consideration," Ansari told a TV news channel.